Overview

• Heavy rains on July 6 triggered red-flag closures of all three designated bathing areas along the Seine.
• The bathing zones at Grenelle, Île Saint-Louis and Bercy opened July 5 as part of a €1.4 billion sanitation upgrade linked to the Paris 2024 Olympics.
• Officials deploy real-time sensor networks to monitor E. coli and enterococci levels daily and must suspend swimming when thresholds are exceeded or after heavy rainfall.
• Access to the free bathing areas is regulated by minimum age, height and swimming-ability requirements with lifeguards and mandatory safety buoys on site.
• Independent water-quality experts warn that bacterial concentrations in the Seine can fluctuate rapidly and question whether the current testing regime can reliably ensure swimmer safety.